The present invention relates to polymer induction bonding. Such bonding is used to encapsulate, weld, forge, bond or set polymer materials.
Current materials used for such bonding are made from a plastic polymer compounded with magnetic particles and heated through an electrical induction energy frequency at a fixed Khz to Mhz single frequency. The material is manufactured as pellet and solid profile material. There are limits in applying the welding material due to the geometry and access in the application specific assembly. The size of the material pellet and profile also limits the application into the assembly.
Various types of materials are known for induction bonding. For example, U.S. Pat. No. 6,048,599 discloses a sheet material for electromagnetic fusion bonding which comprises a plurality of composite electromagnetic portions including susceptor particles uniformly distributed adjacent polymer portions. The composite portions are bonded to each adjacent polymer portion so that the composite portions and the polymer portions form a patterned array of alternating portions.
U.S. Pat. No. 6,056,844 discloses controlled-temperature induction heating of polymeric materials by mixing ferromagnetic particles in the polymer to be heated. Temperature control is obtained by selecting ferromagnetic particles with a specific Curie temperature (Tc). The ferromagnetic particles heat up in an induction field, through hysteresis losses, until they reach their Curie temperature (Tc). At that point, heat generation through hysteresis loss ceases.
U.S. Pat. No. 6,939,477 discloses a temperature-controlled induction heating of polymeric materials wherein an induction coil, which generates a magnetic field, is placed near the material and heats a susceptor, such as a metal screen or powder, within the material to be heated. To improve the induction heating process, the susceptor design is optimized for effective fusion bonding or welding of thermoplastic layers, the method of mixing or placing the susceptor particles within a composite matrix is optimized, and the power infrequency of the induction device are optimized.
U.S. Pat. No. 5,643,390 discloses bonding techniques for high performance thermal plastic compositions in which a thermoplastic material and a thermosetting monomer are selected so that the thermosetting monomer has similar solubility parameters to the thermoplastic material. The thermoplastic material is bonded directly to the surface of the thermosetting monomer to create a co-cured layered material which is processed with either a thermoset adhesive or bonded by fusion.
U.S. Pat. No. 6,137,093 discloses high efficiency heating agents that consist of ferromagnetic fibers for use in alternating magnetic fields.
These prior art induction heating techniques, as well as other known techniques, can provide very fast heating and bonding rates, but exhibit poor control of bond-line temperatures.